Donald Trump is preparing to take office with a broad plan to dismantle many of the environmental policies and priorities established under the Obama administration. And, to the dismay of environmentalists, he’s vowed to make the controversial Clean Power Plan — a proposed rule under the Clean Air Act that would compel power plants throughout the nation to slash their carbon emissions — one of the first rules to be scrapped.

The question that remains is how — and while the threat remains substantial, killing the plan may not actually be that simple, legal experts say.

Currently, the Clean Power Plan is the subject of a highly fraught legal battle being waged in the U.S. Court of Appeals for the District of Columbia Circuit, which will decide whether the proposal’s carbon-cutting requirements overstep constitutional boundaries. The Environmental Protection Agency stands on one side, along with environmental groups, climate activists and even several large corporations, and on the other side are two dozen states, supported by industry groups and utilities.

The rule is a key part of the Obama administration’s broader plan to tackle climate change and reduce domestic greenhouse gas emissions by more than a quarter by the year 2025, relative to their 2005 levels. This ambitious pledge is also the centerpiece of the nation’s individual commitment to the Paris climate agreement (from which Trump has also promised to withdraw, with potentially disastrous global consequences). As such, the fate of the Clean Power Plan has substantial implications, both nationally and internationally.

It could take months for the court to issue a ruling, meaning the process could potentially drag out past the presidential inauguration in January. Even after the D.C. circuit court makes its ruling, regardless of the outcome, it’s almost certain that the case will be appealed to the Supreme Court. The question that remains is how Trump’s administration will choose to handle the ongoing legal proceedings, and what it will do if the rule is upheld.

Once Trump takes office, it’s possible that the new administration could simply decline to continue defending the Clean Power Plan in court, whether by withdrawing from the current proceedings or failing to bring its defense to the Supreme Court in the case of an appeal. But this would hardly kill the rule or bring the litigation process to a halt, experts say.

“There are states and municipalities and environmental and public health organizations that have intervened in the case in support of EPA and the rule,” said Jack Lienke, a senior attorney with New York University School of Law’s Institute for Policy Integrity. “And they have party status, they have standing to defend the rule.”

In other words, even if the Justice Department stepped out, other groups would almost certainly take up the rule’s defense. However, there are other ways the administration could attempt to kill the proposal, even before it makes it out of court.

“There is a possibility that [the new administration] could file what is known as a motion for voluntary remand,” said Frank Rambo, a senior attorney and leader of the clean energy and air program at the Southern Environmental Law Center. When permitted, this action essentially halts the case and allows federal agencies to review the complaints argued by the plaintiffs and potentially revise their rules.

That said, attempting to rewrite the Clean Power Plan under these circumstances would be a complex and time-consuming process involving a public comment period and all of the other hoops required in the federal rule-making process, Rambo added.

“They just can’t do that with a wave of a wand,” he said. And the same would apply if the new administration attempted to change the rule after it’s been upheld in court.

“EPA has finalized this rule, this rule is now law — it’s not as if EPA can say ‘nevermind,’” Lienke said. “It would have to go through a new notice and comment rule-making process as it did when it first issued the rule, and it would need to have rational reasons for undoing it. And that itself would inevitably be litigated.”

Congressional legislation could also kill the rule, Lienke added. “Presumably if both chambers of Congress were to pass some sort of [bill] blocking the Clean Power Plan, and a President Trump wanted to sign it, that would be law, and that would render the litigation over the rule moot,” he said.

Barring any of these possibilities, it’s possible the EPA under the new administration could simply choose to be lenient when working with individual states on their compliance with the rule.

“EPA has a major role in approving state plans to comply with it, and there’s a certain amount of leeway they might try to exercise fulfilling their role in that implementation process,” Rambo said. But he added that environmental organizations could also legally challenge the EPA’s actions in such a scenario.

“Certainly in our states we would be looking very closely at what EPA does,” he said of the Southern Environmental Law Center. “We would be looking very closely at those state plans themselves, and whether EPA approves or disapproves them on those grounds.”

The takeaway is that there are still plenty of checks and balances that will be applied to any action a Trump administration might choose to take against the Clean Power Plan. It doesn’t mean the rule isn’t in major trouble — but it’s unlikely to go down without a fight, either.

“I don’t think panic is called for in any event,” Rambo said. “But I think it’s safe to say that this is one of the instances in which elections have consequences, and the fate of the Clean Power Plan is certainly going to be very different now than it would be if the election had turned out differently.”